Objective:
The objectives of the research project plan are as follows: 1) to evaluate the genotypic and biologic basis of susceptibility to experimentally induced mastitis by Gram-positive and Gram-negative bacteria; 2) to determine the relationship between mastitis and nitro-oxidative stress and develop innovative alternatives to reduce tissue damage; 3) to develop strategies for modulating somatic stem cells to promote the replacement of mammary epithelial cells damaged by mastitis.

Approach:
To evaluate the genotypic and biologic basis of susceptibility to experimentally induced mastitis by Gram-positive and Gram-negative bacteria (Objective 1) we will: 1) evaluate the response of dairy cows with divergent estimated breeding value for somatic cell score, and presumptive differences in mastitis susceptibility and/or responsiveness, to experimental challenge with Gram-negative bacteria; 2) evaluate the mastitis susceptibility of cows that differ with regard to single nucleotide polymorphisms in proinflammatory cytokine promoters, which influence the innate immune response. To determine the relationship between mastitis and nitro-oxidative stress and to further develop innovative alternatives to reduce tissue damage (Objective 2) we will focus on the relationship between oxygen-nitrogen adducts that are generated to combat invading pathogens and damage to mammary tissue, as reflected by increased protein nitration, and develop targeted biochemical interventions to reduce generation of nitrated proteins. We will: 1) evaluate the extent of protein nitration in mammary glands of control and experimentally infected mastitic cows; 2) evaluate the capacity of ' - and d -tocopherols to limit protein nitration during experimentally-induced mastitis by virtue of their ability to neutralize oxygen-nitrogen adducts. To develop strategies for modulating somatic stem cells to promote the replacement of mammary epithelial cells damaged by mastitis (Objective 3) we will: 1) evaluate the ability of xanthosine to promote the expansion of mammary stem cells and study the genomic response to xanthosine treatment in order to uncover critical regulatory pathways and stem cell modulators; 2) evaluate potential markers for bovine mammary stem cells that we identified in previous transcriptome analyses (This will facilitate future mammary stem cell research); 3) Evaluate the ability of regulators of the p53 pathway, or other stem cell stimuli, to promote repair of mammary tissue that is damaged by mastitis.